1. Field of the Invention
The present invention relates to an image forming apparatus and a paper feeding mechanism for the same. More particularly, the present invention relates to a paper feeding mechanism for an image forming apparatus that is capable of compensating for differences in the velocities of rollers that convey paper.
2. Description of the Related Art
Generally, in an electrophotographic image forming apparatus such as a laser printer, an electrostatic latent image is formed on a photoconductive medium, such as a photoconductive belt or drum, and the electrostatic latent image is developed using developer of a certain color and transferred onto paper, thereby producing a desired image.
FIG. 1 schematically shows a printing process in a conventional image forming apparatus 1. Referring to FIG. 1, the surface of a photoconductive drum 3 is evenly charged by an electrifying roller 2. The photoconductive drum 3 is exposed to a laser beam generated by a laser scanning unit 5 to form an electrostatic latent image. The electrostatic latent image is developed using toner into a visible image by a developing roller 7 that rotates in contact with the photoconductive drum 3.
Paper stacked on a paper supply part 9 is supplied to a feeding roller 13 by a pickup roller 11 and conveyed to a transferring roller 15 by rotation of the feeding roller 13. The developed toner image formed on the photoconductive drum 3 is transferred onto the paper by pressure generated by the transferring roller 15. The transferred toner image is fixed with a high temperature by a fixing roller 17 and conveyed toward a discharged-paper tray 21 by a discharging roller 18. As a result of these processes, a desired image is printed onto paper.
Conventional image forming apparatuses have been further developed to include dedicated paper supplying cassettes, such as a multistep paper supply, so that the paper supply capacity can be increased. Laid-Open Korean Patent Application No. 1998-020607(laid open on Jun. 25, 1998, and entitled “Feeding Device of Electrophotographic Process”) discloses an example of such an image forming apparatus, and is hereby incorporated by reference in its entirety.
Recently, a variety of functions have been, and are being, added to a basic image forming apparatus, as disclosed in the above example. The addition of functions produces an added emphasis on making smaller, more compact products.
In a conventional image forming apparatus, however, it is difficult to reduce the size of the apparatus. One source of difficulty is the use of a dedicated feeding roller 13. The use of a dedicated feed roller, in combination with a pickup roller 11, to feed paper to the photoconductive drum 3, increases the length of the paper feeding path 23. Accordingly, the size of the entire apparatus is increased. Furthermore, the dedicated feeding roller 13 increases the number of parts in the apparatus, thereby increasing manufacturing costs.